Power metal-oxide-semiconductor field-effect transistor (MOSFET) devices, such as vertical diffused metal oxide semiconductor (VDMOS) devices, are used in power application devices because they complement both bipolar devices and complementary metal-oxide-semiconductor CMOS devices through bi-polar-CMOS-DMOS (BCD) processes. For example, VDMOS devices may be used in power supplies, buck converters, and low voltage motor controllers to furnish power application functionality.
The on-state resistance (“RON”), the maximum breakdown voltage (“BVDSS”), and the overall capacitances of the device are important characteristics of VDMOS designs. These characteristics are important operating parameters of the VDMOS devices, which dictate the applications with which the devices may be utilized. On-state resistance is usually dependent upon the design and layout of the device, the process condition, temperature, drift region length, doping concentration of the drift region, and the various materials used to fabricate the devices. Breakdown voltage is defined as the largest reverse voltage that can be applied to the drain of the transistor without causing an exponential increase in the current. Moreover, various parasitic capacitances in the devices lead to reduced operating frequency.